A FIELD STUDY OF THE INFLUENCE OF ORGANIC MAT- 

 TER UPON THE WATER-HOLDING CAPACITY OF A 

 SILT-LOAM SOIL ' 



By Frederick J. Alway, Chief of Division of Soils, and Joseph R. Nuhh^K, formerly 

 Assistant in Soils, Agricultural Experiment Station of the University of Minnesota 



INTRODUCTION 



It has long been believed that the increased amount of organic matter 

 in the soil resulting from applications of manure causes an important 

 and beneficial increase in the water supply of crop plants, it both 

 enabling the water to be absorbed more readily during heavy rains and 

 increasing the amount held against downward movement, thus retaining 

 a more generous supply within reach of the roots of the crop plants. 



Thorne, in a recent paper (12),'^ has raised the question whether or- 

 ganic matter 



possesses a value for soil improvement additional to that of the nitrogen and mineral 

 elements that it may contain 



and attributes (/>. 27) the physical improvement of the soil following the 

 use of manure 



not to the carbonaceous matter of the manure, but to the superior growth of plant 

 roots induced by the nitrogen and mineral elements carried by the manure. 



His conclusions are based chiefly upon data from experiments at the 

 Ohio Experiment Station covering a period of 24 years, in which the 

 recovery of nitrogen, phosphorus, and potassium has been higher from 

 sodium nitrate, acid phosphate, and potassium chlorid than from farm 

 manure. As the Ohio experiments 



have been conducted on a soil depleted of its organic matter by a long period of tenant 

 husbandry before the test began and the average yields of the tmtreated land diu"ing 

 the period of the test have been only 7.85 bushels per acre of wheat, 14.70 bushels of 

 com and 21.76 bushels of oats {12, p. 26), 



the results would suggest that we have been in the habit of overrating 

 the benefit derived from any increased water-holding capacity of the soil 

 caused by the application of manure, or even that the effect of the added 

 organic matter upon this property may in reality be too slight to have 

 any practical importance. 



Entirely satisfactory fields for studies designed to determine the effect 

 of differences in the content of organic matter upon the water-holding 

 capacity of soils are scarce; and with most field soils the bringing about 

 of an appreciable increase through applications of manure as light as those 



1 Published, with the approval of the Director, as Paper 150, of the Journal Series of the Minnesota Agri- 

 cultural Experiment Station. 

 ^ Reference is made by niunber (italic) to " Literature cited," p. 277-278. 



Journal of Agricultural Research, Vol. XVI, No. 10. 



Washington, D. C. Mar. 10, 1919. 



ro Key No. Minn.-37. 



(263) 



